They're going to bring a lot of attention to your school, and they're going to piss a lot of people off, so CAPITALIZE on that attention -- don't just ignore it/turn the other cheek.

Set up some kind of charity for Officer Deriek's family or donate to an existing charity for LGBTQ rights/etc. Ask people walking by to donate to whatever they can. After walking by the WBC, I'd sure as hell be pissed off enough to donate whatever I had in my wallet.

You can even set up a charity thermometer, so the WBC can see how much money THEY'RE raising for whatever charity they're "morally against." (I saw this on youtube somewhere; definitely not my idea.)